In this research work the main objective was studying the use of kn type factorial programs for modeling and optimization of the milk fermentation process in the presence of hydrotalcite. The milk fermentation is considered the principal phase in yoghourt technology. The yoghourt is a product resulted from the fermentation of the lactic acid under the action of two specific lactic bacteria: Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. Using the experiment programming method, the mathematical model that corresponds to the answer function (the yoghourt acidity) is obtained, allowing simulation individual or interacting effects between parameters. According to the experimental program, which was used, and the variation of parameters interval, the real optimal values of parameters can be obtained, in the initial field or not.